That's ... rather bizarre. I'm using an NEC 17" CRT connected to an FIC Radeon 9200 via the DVI-VGA converter as we speak, and I haven't noticed anything too unusual about the "white" background color, as compared to the 15" Compaq CRT that I have connected to the VGA port, although I don't have them side-by-side. It's a little fuzzy, but I have it connected through a mechnical switchbox to extend the cable length, so that would be the reason. (Err, actually, I think that I have the Compaq on the DVI-VGA adaptor, and the NEC on the VGA port. Regardless, I haven't noticed what you are describing on that monitor either.)
I *have* had some wierd cold/warm boot display-corruption/freeze problems, and some issues with ATITool. I'm running the ocfaq.com softmod Cat 4.6 driver package. Haven't been able to reliably overclock, and in fact, even at stock speeds, leaving the ATITool running with the 3D window open for a long period of time, causes really wierd corruption and system instability.
I have an MSI KT4V-L mobo, with Via KT400/8235 chipset. There have been some reported issues with AGP 8x instability on this board, and I'm wondering if that's part of the problem or not.
Even though ATITool causes problems, I've not had any problems running the UT2K4 demo for an hour or two, although there was one time when I ALT+TAB'ed away from it, and couldn't go back.